Generally, various kinds of containers using a sprayer form or having a vacuum pumping device are used so that a cosmetic product or detergent in a liquid or gel state may be easily taken off and used. In particular, in case of a solution which should not contact oxygen, a vacuum pumping device is used to minimize a contact between the solution and oxygen, and the solution is contained in a container provided with a vacuum pump which is used for taking off the solution when necessary. Such a vacuum pumping device is disclosed in Korean Patent Registration No. 10-875906. Korean Patent Registration No. 10-875906 discloses that a cylinder and a piston are provided at a handle to take off a content from the container, and the content is discharged to a desired point by using the piston. In particular, a housing cap mounted to the top of the container and a cylinder detachably mounted to the housing cap are coupled in a threaded pattern.
However, if the above liquid container having a vacuum pumping device is used, since the cylinder is coupled and separated in a threaded pattern, the cylinder should be manipulated to make at least one turn, namely several turns. Therefore, whenever the liquid container is used, the locking state of the threaded coupling should be repeatedly adjusted, and the user should make repeated turns in a clockwise or counterclockwise direction, which is very cumbersome to use. In addition, an elastic cap with a complicated design is used for opening or closing the neck portion of the container, which is not easily fabricated. Moreover, if the elastic cap is opened or closed repeatedly, its elastic force deteriorates, and therefore the degree of sealing deteriorates as time goes, which results in introduction of air or alien substances. Further, when it is intended to discharge a content by pushing the piston, since the maximum static friction force between the piston and the cylinder is higher than a driving frictional force between the piston and the cylinder, the piston is strongly pressed when the piston is actually operated. Therefore, the content filled in the cylinder, particularly the content with low viscosity, is ejected under too strong pressure, which causes the content to be discharged more than required.
Therefore, in order to solve such problems, there is a need to develop a liquid container having a vacuum pump device, which may be easily manufactured due to a simple piston design, may be isolated from an external air regardless of use time by using an elastic cap, and may prevent the air from penetrating therein while the vacuum pump is inserted.